This invention generally relates to a housing or other hollow device for intracorporeal use such as performing a therapeutic or diagnostic procedure within a body lumen or cavity within the housing. The housing is particularly useful with a catheter for removing tissue from a body lumen or cavity, such as the removal of atheroma from a patient's artery in an atherectomy procedure.
In typical coronary atherectomy procedures, a guiding catheter having a preshaped distal tip is percutaneously introduced into a patient's cardiovascular system through the femoral artery and advanced therein until the preshaped distal tip of the guiding catheter is disposed within the ascending aorta adjacent the ostium of the coronary artery in which the procedure is to be performed. The guiding catheter is twisted or torqued from the proximal end, which is outside the patient, to turn the distal tip of the guiding catheter so that it can be guided into the desired coronary ostium. An atherectomy catheter having a cutter head on its distal end is introduced into and advanced through the guiding catheter and out the distal tip thereof until the cutter head is properly positioned across the lesion to be treated. Once properly positioned, a positioning balloon on one side of the cutter head is inflated with liquid at relatively high pressures (e.g., 3-6 atmospheres) to press the cutter head against the stenotic tissue to be removed so that such tissue will be urged into the interior chamber of the cutter head where a cutting blade severs the tissue from the artery wall. The positioning balloon is then deflated so that the atherectomy catheter can be repositioned, e.g. rotated, to remove additional tissue from the stenosis in essentially the same manner. When the procedure is completed, the positioning balloon is finally deflated and the catheter removed from the artery so that blood flow can resume through the artery. In commercially available atherectomy catheters such as the Simpson Atherocath.RTM., which is available from the assignee of the present application, Devices for Vascular Intervention (DVI), the cutter blade is axially rotated a relatively high speeds, e.g. 2000 rpm while the blade is advanced from one end of the housing to the other in order to sever the stenotic tissue which is urged into the interior chamber.
Reference is made to U.S. Pat. No. Re. 33,569 (Gifford, III et al.), U.S. Pat. No. 4,771,774 (Simpson et al.), and U.S. Pat. No. 5,092,873 (Simpson et al.) which describe further details of atherectomy catheters and which are incorporated herein in their entirety by reference.
The cutter housing on most atherectomy catheters have been formed of high strength materials such as stainless steel. As a result, they have been rather stiff and this stiffness has been found to significantly restrict the ability of the atherectomy catheter to be advanced through tortuous arterial anatomy and to limit how far an atherectomy catheter can be advanced within a patient's arterial system. Softer, more flexible materials might be employed to form the cutter housing but when the housing is made of softer, more flexible materials, the housing can deform, e.g. kink, when being advanced through the shaped distal end of the guiding catheter or tortuous arterial anatomy so that the cutting blade within the housing cannot be properly moved within the inner chamber of the cutter housing for effective tissue removal. It has also been found that, if the housing is too soft or becomes deformed in the procedure, the cutting blade frequently will not remain within the inner chamber of the cutter housing as it is advanced through the inner chamber to sever tissue, thereby preventing the completion of the procedure. Moreover, in the latter instance the excursion of a rotating cutting blade through a side opening or window in the cutter housing can cause serious damage to the arterial wall. If the cutting blade cannot be withdrawn back into the inner chamber of the cutter housing through the window, there can be difficulties in withdrawing the atherectomy catheter back into the guiding catheter, requiring the removal of both the atherectomy catheter and the guiding catheter. If both the guiding catheter and the atherectomy catheter must be removed, replacement catheters would have to be advanced through the patient's arterial system, increasing considerably the length and the cost of the atherectomy procedure.
What has been needed and has been heretofore unavailable is a relatively flexible cutter housing for an atherectomy catheter which allows for effective cutting operations, which maintains its shape and which retains the cutting blade within the inner chamber of the housing during the procedure. The present invention satisfies these and other needs.